A light emitting diode (LED) has been developed using a characteristic in which a light emitting phenomenon occurs when a voltage is applied to a compound semiconductor. The LED is smaller than conventional light sources, and has a long life span and superior efficiency for converting electric energy into light energy. Particularly, as white LEDs with high luminance are commercialized by virtue of the development of semiconductor technologies, various lighting apparatuses using the white LEDs has appeared.
Especially, research and development have been actively conducted in relation to an LED module for illumination, in which a plurality of LED elements are integrated in a large scale to have a shape in which they are arranged in series and parallel, so that intensity of light per unit area, i.e., luminance, can be enhanced by a few thousands cd/m2 or more, thereby being illuminated at a sufficiently long distance.
However, as the integration scale of the LED module is increased, heat generated in the same area is also increased. For this reason, there is a problem in that an LED element may be damaged due to a large amount of heat generated from the LED element.
As a conventional LED module for illumination used to solve such a problem, there is an LED module capable of enhancing heat radiation performance by integrating LED elements on a metal printed circuit board (PCB) with a heat radiation effect superior to a general PCB. The metal PCB is a printed circuit board capable of enhancing heat radiation performance by attaching a flexible PCB formed of a synthetic resin film to a top portion of a radiator made of a metal component with high thermal conductivity through an adhesive agent.
However, since heat transfer from the LED elements to the lower radiator is hindered by the flexible PCB with low thermal conductivity and the adhesive agent, which are positioned between the LED elements and the radiator, there is limitation to radiate a large amount of heat generated by integrating the LED elements in a large scale. Consequently, there is a problem in that an LED element may be damaged due to heat generated in light emission.